74 Dairy Bacteriology. 



Soapy milk: A soapy flavor in milk was traced by Weig- 

 mann and Ziru * to a specific bacillus, B. lactis saponacei, 

 that they found gained access to the milk in one case from 

 the bedding and in another instance from ha} r . A similar 

 outbreak has been reported in this country, 2 due to a germ 

 acting on the casein and albumen. 



Red milk. The most common trouble of this nature 

 in milk is due to presence of blood, which is most fre- 

 quently caused by some wound in the udder. The inges- 

 tion of certain plants as sedges and scouring rushes is also 

 said to cause a bloody condition; madders impart a red- 

 dish tinge due to coloring matter absorbed. Defects of this 

 class can be readily distinguished from those due to germ 

 growth because they are apparent at time of milking. 

 Where blood is actually present, the corpuscles settle out 

 in a short time if left undisturbed. 



There are a number of chromogenic or color-producing 

 bacteria that are able to grow in milk, but their action is 

 so slow that generally they are not of much consequence. 

 Moreover their development is usually confined to the sur- 

 face of the milk as it stands in a vessel. The most import- 

 ant is the well-known B. prodigiosus. Another form found 

 at times in milk possessing low acidity 3 is B. lactis erythro- 

 genes. This species only develops the red color in the dark. 

 In the light, it forms a yellow pigment. Various other 

 organisms have been reported at different times. 4 



Blue milk. Blue milk has been known for many years, 

 its communicable nature being established as long ago as 

 1838. It appears on the surface of milk first as isolated 



Miloh Zeit. 22:5(59. 



'Marshall, Bull. 146, Mich. Expt. Stat., p. 16. 



Grotenfelt, Milch Zeit., 1833, p. 283. 



Menge, Cent. f. Bakt., 6:590; Keferstein, Cent. f. B?.kt., 21:177. 



